Synonyms for Chronic:

adj.

continuing (adjective)
long-lived.
deep-rooted (adjective)
ingrained.
habitual (adjective)
habitual, recurrent, routine.
incessant, never-ending (adjective)
unabating, rooted, stubborn, Recurring, obstinate, long-lived, routine, habitual, confirmed, settled, ceaseless, enduring, ingrained, prolonged, persisting, lifelong, deep-seated, lingering, fixed, continual, constant, tenacious, lasting, ever-present, sustained, continuous, abiding, perennial, incurable, unyielding, inbred, persistent, usual, inveterate, deep-rooted, long-standing, recurrent, inborn, protracted.
regular (adjective)
continual, monotonous, standard, routine, prevailing, commonplace, ordinary, rhythmic, regular, Predominating, common, habitual, everyday, universal, traditional, average, recurrent, accustomed, frequent, metronomic, canonical, usual, steady, periodic, conventional, orthodox, constant, general, stock, mundane, cyclical, customary, epochal, normal, Familiar.

n.

pitiful, bad, dire, poor, second-rate, disgraceful, low-grade, terrible, embarrassing. delicate, difficult, testing, awkward, critical, intractable, thorny, trying, Habituated, impossible, intolerable. way of life, custom, habit, daily life, as is someone's wont, ritual, tendency, common practice, take to. chronic (noun)
confirmed, degenerative, inveterate, habitual, addicted, prolonged.

Other synonyms:

benign, protracted, lingering, communicable, stubborn, asymptomatic, autoimmune, congenital, catching, clinical. incurable, low-grade, Habituated. hardened, bad. advanced. persistent.

Usage examples for chronic

  1. One plastic nurse lost a chronic case. – Our Nervous Friends Illustrating the Mastery of Nervousness by Robert S. Carroll
  2. It also suits certain feeble stomachs, and has been thought most advantageous in chronic diseases. – The Physiology of Taste by Brillat Savarin
  3. Pius is in a chronic state of extreme irritation. – Letters From Rome on the Council by Johann Joseph Ignaz von Döllinger